The prevalence of obesity, a condition leading to several comorbidities including hypertension, dyslipidemias, coronary heart disease, stroke as well as several malignancies is on the rise in the US and worldwide leading to increasing morbidity and mortality. The mechanisms underlying the pathogenesis of obesity and associated conditions have not yet been elucidated and currently available therapeutic approaches are far from optimal. In the past few years, the scientific community realized that the adipose tissue is not an inert depot storage organ but an active endocrine organ secreting several hormones. We have thus been researching the biochemistry, physiology, pathophysiological importance and therapeutic significance of adipose tissue secreted hormones, i.e. adipokines, aiming at elucidating their function in humans. Although important and clinically useful new information has been accumulated and new compounds have been advanced to phase III clinical trials in humans (leptin, adiponectin inducing agents etc) several questions still remain. What is the role of novel adipokines? What physiological functions do they serve and how could we prove the concept of their clinical efficacy? How do they interact with other known hormones or novel, muscle secreted hormones, to alter energy homeostasis and metabolism? How could we exploit novel information to create clinical interventions to fight obesity and its complications? Addressing these and similar questions and training dedicated scientists, who by focusing on these questions will function as power multipliers, could lead to a substantial beneficial impact on clinical medicine and public health. Now an experienced mid-career clinical researcher, I have undertaken a series of patient-oriented research studies that contribute significantly towards addressing these important issues. This proposed K24 award will allow me and my mentees to continue focusing intensively on this area of research for the next five years, a critical period for the development of this field. Importantly, this K24 award will not only be expanding my potential for significant contributions in the field but will primarily be, by design of the K24 awards, the appropriate vehicle for nurturing the next generation of patient-oriented researchers in this field. The specific aims of this proposal are: 1. To provide a nourishing professional environment for the training and advancement of the careers of beginning clinical researchers, who will be conducting studies within ongoing patient-oriented research projects in the area of physiology and therapeutic use of molecules important in the regulation of energy homeostasis, and 2. To supplement already funded research projects aiming at examining the role of adipokines, gastrointestinal tract secreted molecules and myokines in metabolic diseases including obesity, diabetes and associated comorbidities. As expected based on NIH guidelines, the work performed under this K24 grant will be building upon the infrastructure provided by prospective cohort studies, pharmacokinetic studies, ?proof of concept? clinical trials, and multicenter phase III-IV clinical trials already underway or planned.